Bifenox is the

ISO The International Organization for Standardization (ISO ; ; ) is an independent, non-governmental, international standard development organization composed of representatives from the national standards organizations of member countries. Me ...

common name In biology, a common name of a taxon or organism (also known as a vernacular name, English name, colloquial name, country name, popular name, or farmer's name) is a name that is based on the normal language of everyday life; and is often con ...

for an

organic compound Some chemical authorities define an organic compound as a chemical compound that contains a carbon–hydrogen or carbon–carbon bond; others consider an organic compound to be any chemical compound that contains carbon. For example, carbon-co ...

used as an

herbicide Herbicides (, ), also commonly known as weed killers, are substances used to control undesired plants, also known as weeds.EPA. February 201Pesticides Industry. Sales and Usage 2006 and 2007: Market Estimates. Summary in press releasMain page f ...

. It acts by inhibiting the enzyme

protoporphyrinogen oxidase Protoporphyrinogen oxidase or protox is an enzyme that in humans is encoded by the ''PPOX'' gene. Protoporphyrinogen oxidase is responsible for the seventh step in biosynthesis of protoporphyrin IX. This porphyrin is the precursor to hemoglobin, ...

which is necessary for

chlorophyll Chlorophyll is any of several related green pigments found in cyanobacteria and in the chloroplasts of algae and plants. Its name is derived from the Greek words (, "pale green") and (, "leaf"). Chlorophyll allows plants to absorb energy ...

synthesis Synthesis or synthesize may refer to: Science Chemistry and biochemistry *Chemical synthesis, the execution of chemical reactions to form a more complex molecule from chemical precursors **Organic synthesis, the chemical synthesis of organi ...

History

The nitrophenyl ethers are a well-known class of herbicides, the oldest member of which was nitrofen, invented by Rohm & Haas and first registered for sale in 1964. This area of chemistry became very competitive, with the Mobil Oil Corporation's filing in 1969 and grant in 1974 of a patent to the

structural analog A structural analog, also known as a chemical analog or simply an analog, is a chemical compound, compound having a chemical structure, structure similar to that of another compound, but differing from it in respect to a certain component. It can ...

with a COOCH₃ group adjacent to the nitro group of nitrofen. Bifenox was launched with the

brand name A brand is a name, term, design, symbol or any other feature that distinguishes one seller's goods or service from those of other sellers. Brands are used in business, marketing, and advertising for recognition and, importantly, to create and ...

Mowdown in 1981. Meanwhile Rohm & Haas had patented and developed acifluorfen (as its sodium salt with brand name Blazer) in 1980. Both compounds had much improved properties including a wider spectrum of herbicidal effect and good safety to some crops, including

soybean The soybean, soy bean, or soya bean (''Glycine max'') is a species of legume native to East Asia, widely grown for its edible bean. Soy is a staple crop, the world's most grown legume, and an important animal feed. Soy is a key source o ...

Synthesis

Bifenox was first synthesized by R.J. Theissen of the agricultural research section of Mobil Chemical's Central Research Laboratory in 1969 . Bifenox synthesis

The preparation of bifenox first described in the Mobil patent includes as its final step an

Ullmann condensation The Ullmann condensation or Ullmann-type reaction is the copper-promoted conversion of aryl halides to aryl ethers, aryl thioethers, aryl nitriles, and aryl amines. These reactions are examples of cross-coupling reactions. Ullmann-type reaction ...

between the potassium salt of 2,4-dichlorophenol and methyl 2-nitro-5-chlorobenzoic acid. The methyl 2-nitro-5-chlorobenzoic acid was made starting from Toluene/Chlorine/benzoic acid/Methanol/nitric acid/ in a 5 steps synthesis http://www.microchem.fr/patent_alas/process_info/bifenox/bifenox.html

Mechanism of action

The detailed mechanism of action for nitrofen, acifluorfen and related diphenyl ether herbicides was unknown at the time they were invented. The effects visible on whole plants are

chlorosis In botany, chlorosis is a condition in which leaves produce insufficient chlorophyll. As chlorophyll is responsible for the green color of leaves, chlorotic leaves are pale, yellow, or yellow-white. The affected plant has little or no ability to ...

and

desiccation Desiccation is the state of extreme dryness, or the process of extreme drying. A desiccant is a hygroscopic (attracts and holds water) substance that induces or sustains such a state in its local vicinity in a moderately sealed container. The ...

: several hypotheses were advanced regarding the molecular-level interactions which might explain these symptoms. The now-accepted explanation for the damage is that these compounds inhibit the enzyme

, which leads to an accumulation of

protoporphyrin IX Protoporphyrin IX is an organic compound, classified as a porphyrin, that plays an important role in living organisms as a precursor to other critical compounds like heme (hemoglobin) and chlorophyll. It is a deeply colored solid that is not sol ...

in the plant cells. This is a potent

photosensitizer Photosensitizers are light absorbers that alter the course of a photochemical reaction. They usually are catalysts. They can function by many mechanisms; sometimes they abstract an electron from the substrate, and sometimes they abstract a hydro ...

which activates oxygen, leading to

lipid peroxidation Lipid peroxidation, or lipid oxidation, is a complex chemical process that leads to oxidative degradation of lipids, resulting in the formation of peroxide and hydroperoxide derivatives.{{Cite journal , last1=Ayala , first1=Antonio , last2=Muñoz ...

. Both light and oxygen are required for this process to kill the plant.

Uses

Bifenox is not currently used in the United States although in 1981 it had been subject to a full regulatory review, under the then-new "Registration Standard" process. Within the European Union, a 2-tiered approach is used for the approval and authorisation of pesticides. Firstly, before a formulated product can be developed for market, the active substance must be approved for the European Union. After this has been achieved, authorisation for the specific product must be sought from every Member State that the applicant wants to sell it to. Afterwards, there is a monitoring programme to make sure the pesticide residues in food are below the limits set by the

European Food Safety Authority The European Food Safety Authority (EFSA) is the agency of the European Union (EU) that provides independent scientific advice and communicates on existing and emerging risks associated with the food chain. EFSA was established in February 2002 ...

. Bifenox is registered for use against weeds in crops including cereals, soybeans, sugarbeet and rice. In Switzerland, some of its

formulations Formulation is a term used in various senses in various applications, both the material and the Abstract object, abstract or wikt:formal, formal. Its fundamental meaning is the putting together of components in appropriate relationships or struc ...

can be used in lawns and orchards. Bifenox is normally applied postemergence (when weeds are visible in the crop). It controls or suppresses a wide range of species including ''

Capsella bursa-pastoris ''Capsella bursa-pastoris'', known as shepherd's purse or lady's purse because of its triangular flat fruits, which are purse-like, is a small annual and ruderal flowering plant in the mustard family (Brassicaceae). Scientists have referred to ...

'', ''

Galium aparine ''Galium aparine'', with common names including cleavers, clivers, catchweed, robin-run-the-hedge, goosegrass, and sticky willy, is an annual, herbaceous plant of the family Rubiaceae. Names ''Galium aparine'' is known by a variety of common n ...

'', ''

Lamium purpureum ''Lamium purpureum'' (from Latin ''purpureum'' – purple), known as red dead-nettle, purple dead-nettle, or purple archangel, is an annual herbaceous flowering plant. It is native to Eurasia but can also be found in North America. Description ' ...

'', ''

Myosotis arvensis ''Myosotis arvensis'' or field forget-me-not is a herbaceous annual plant, annual to short lived perennial plant, perennial flowering plant in the family Boraginaceae. It is native to Europe, Turkey, the Caucasus, Siberia, the western Himalayas, ...

'', ''

Papaver rhoeas ''Papaver rhoeas'', with common names including common poppy, corn poppy, corn rose, field poppy, Flanders poppy, red poppy, and Odai, is an annual herbaceous species of flowering plant in the poppy family Papaveraceae. It is native to north Afr ...

'', '' Veronica hederifolia'', '' Veronica persica'' and '' Viola arvensis''. The product is typically used at application rates of 720 g a.i. per hectare.

References

External links

* * Bifenox synthesis : https://www.microchem.fr/patent_alas/process_info/bifenox/bifenox.html {{commons category, Bifenox PPO herbicides Nitrobenzene derivatives Methyl esters Chlorobenzene derivatives Group 14 herbicides